The invention provides a robust connection interface for surface mount technology (SMT) contacts used in the manufacture of electronic devices that have high area densities or high wear environments, and that accommodates contact surface irregularities without significant wear to the either contact surface.
In SMT contacts, connector components are applied directly to the surface of a circuit board. The components are secured at specified locations on the circuit board by solder pads that are placed on the circuit board in a suitable process, such as by printing the pads on the board forming a printed circuit board (PCB). The solder pads are then heated and the various components are placed onto the solder pads to be secured to the PCB by the cooling solder pads bonding the components to the PCB.
In the manufacture of the PCBs, to provide electrical connection to external or peripheral components various SMT style connectors are used, including but not limited to: Land Grid Arrays (LGAs), Ball Grid Arrays (BGAs), Pin Grid Arrays (PGAs), Flexible Flat Cable (FPC) connectors, and Pogo™ contacts. These connectors or components are usually soldered to one side of the circuit board and require a mating connector affixed to the external component.
In one prior art embodiment, as illustrated in FIG. 1, the component secured to the PCB 10 is a connector 18 used to interconnect the PCB 10 with another PCB or with a cable/flex circuit 20 having a complementary connector 26 thereon that is operably connected to another part of the device. These connectors 18,26 each include a body with complementary connecting structures thereon, as well as tabs 14 utilized to connect the connector body 18,26 to the associated PCB 10,20 using the solder pads 12. The connecting structures 16,24 can take various forms, such as POGO pins and rigid metal contacts, or the tubular mating sockets configured to receive the pins or rigid metal contacts, which in FIG. 1—are tensioned, U-channels or sockets of metal, 16 and rigid, U-shaped tabs, 24. The pins, contacts, e.g., a bed-of-nails contact array, or other connectors 24 are pressed into engagement with a suitably formed mating connector, such that an electric connection can be formed between the pin or contact 24 and socket 16 of the mating connector. To facilitate the connection between the contact 24 and the socket 16, the contact and/or the socket, of whatever form, often include a electrical connection-enhancing surface coating on the exterior of the contact(s) 24 and/or socket(s) 16.
One significant drawback with regard to these connectors is that the materials utilized to form the contacts are normally formed of a rigid material in order to facilitate the conductivity or electrical connections between the contacts and the other PCB or device with which the contacts are engaged. As a result, the contacts are formed with various surface irregularities that, when subjected to repeated connect/disconnect cycles, can damage the materials forming the contacts themselves or the contact that is pressed into engagement with the contact containing the surface irregularity. Also, if an excessive or shear force is inadvertently exerted to engage the connectors with one another, it is possible to permanently deform and/or damage the shape of the contacts and/or the coatings on the contacts, thereby degrading the connection between the contacts and other contacts that may be subsequently engaged with the damaged contacts.
Further, even without significant damage to the structure of either contact surface, surface irregularities can cause the interface to be unstable or not possible without exerting additional, potentially destructive force to the contacts already engaged.
Additionally, as with all surface mount devices employing rigid electrical traces, bending or flexing due to thermal expansion, pressure or vibration can cause solder and metal trace materials to fracture, irreparably damaging the contact; which in the case of many connection styles will require full replacement of the connector.
Accordingly, it is desirable to develop an electrical contact structure for use in SMT applications and in the devices constructed thereby that can successfully accommodate structural irregularities on other contact structures to minimize potential damage to the various contact structures and to maximize the electrical connections formed between the contacts.